Navigating The Underground Harbour Area
The Underground Harbour is one of those areas that looks straightforward on the map but quickly becomes a navigation nightmare if you aren't paying attention. I spent about two hours last week mapping out the exact route because the official guide gets a few things wrong, and I want to save you that time. First, you need to understand the layout before you even step in. The Harbour has three main zones: the flooded entry corridor, the central dock area, and the raised walkway system that wraps around the upper level. Most players miss the field guide page because they only clear the ground floor and assume that's the whole area. It's not.
Collect The Field Guide Page In The Underground Harbour
The page itself is located in the upper walkway section, tucked behind a collapsed grate near the easternmost platform. You can reach it two ways. The intended route requires solving a simple water-level puzzle on the ground floor — three pressure plates along the far wall need to be activated in the correct order, which triggers a floodgate that raises the water and reveals a hidden passage. The correct sequence is plate one, then three, then two. If you hit them in the wrong order, the room resets and you have to start over. I know this because I walked away from my setup three times before finally committing the pattern to muscle memory. The shortcut route involves dropping into the lower maintenance tunnels beneath the dock. These are marked on your map as unexplored sewer lines. Once inside, you follow the dry tunnel west for roughly thirty seconds of gameplay time, then climb a ladder hidden behind some pipe clutter. This ladder deposits you directly onto the upper walkway, bypassing the puzzle entirely. The tradeoff is that the maintenance tunnels contain two enemies that guard the path, so if you're under-leveled you might want to just bite the bullet and do the puzzle. Here's what nobody tells you about the field guide page location: the page only spawns if you haven't already collected the previous underground chapter page. If you skipped ahead or picked up related collectibles out of order, the game simply won't place the item there. I ran into this exact issue during a playthrough where I was trying to speedrun the collection. I backtracked three times before realizing the prerequisite collectible order mattered. Check your log first.
The page appears as a slightly glowing parchment object on a small reading stand. Interact with it and it immediately transfers to your field guide. No cutscene, no fanfare. You're done.
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What To Watch Out For
The biggest problem players face is mistaking decoy pages for the real one. There is a second field guide–style item in the same general area — a torn journal fragment on the ground floor near the western dock crates. It looks similar at a glance but does nothing when you pick it up. It's purely flavor text. Don't waste time analyzing it and move on. Another issue is timing. If you're playing on a version where the harbour floods dynamically based on weather events, the water level can change mid-exploration. During heavy rain events, the lower tunnels become partially submerged and the shortcut route is temporarily blocked. You'll need to wait for the weather to clear or use the puzzle route instead. I learned this the hard way when I tried the tunnel path during a storm and ended up swimming back to the entrance three times before realizing what was happening. If you get stuck, the simplest workaround is to use the map marker system. Some players don't realize you can leave custom pins on the Underground Harbour. Drop a pin at the collapsed grate near the eastern platform and the game will highlight the path through the upper walkway. This is genuinely useful if you've lost your way in the maze-like corridors.
There's also a minor bug worth noting. On certain hardware configurations, the field guide page fails to register as collected if you interact with it while running rather than standing still. If you pick up the page and your guide doesn't update, try leaving and re-entering the area, then approach the stand slowly and press the interact button without moving your character. That fixed it for me on my last run.
